This invention relates to a lithography method and apparatus, more particularly but not exclusively, for fabricating 3-dimensional micro or nanostructures.
Over the past decades, progress in micro-fabrication processes has fueled the development of compact, small, light-weight, fast, reliable, and inexpensive sensors and actuators, thus opening up a huge variety of applications in science and industries. With these small sensors and actuators, portable or handheld measurement devices such as miniature spectrometers become possible. These handheld or portable measurement devices enable on-site measurements and this has created a new, rapidly evolving technology with a growing demand. Besides having a plethora of devices developed for the visible and near infrared part of the electromagnetic spectrum, infrared spectrometers that cover larger portions of the infrared range like mid-infrared (MIR) and far-infrared (FIR) offer a huge variety of applications, ranging from quantitative to qualitative analysis of substances needed in chemical, food, pharmaceutical, recycling, petroleum and hydrocarbon processing industries.
The workhorse among such IR spectrometers is the Fourier transform interferometer (FTIR). They are based on interferometers like the Michelson interferometer in which optical components such as mirrors are mechanically scanned to cover a certain spectral range. However, when it comes to measuring time-dependent processes and, in particular, short non-repetitive pulsed signals, the time needed for a mechanical scanning cycle restricts such FTIRs to rather slow processes. Furthermore, the mechanical scanning also leads to an inherent sensitivity to mechanical vibrations which may corrupt the spectral information. Furthermore, Michelson-type FTIRs, the most commonly-used interferometer, inherently reflect 50% of the source radiation back to the source without making use of it. On the other hand, another type of spectrometers which are grating and filter based, allow static and fast detection but are limited to narrow spectral bands. Moreover, the dispersion of light into its spectral components as in the case of grating spectrometers results in less sensitivity to detect small signals (no multiplexing).
It is an object of the present invention to provide a lithography method and apparatus which may be used to fabricate a three dimensional structure for use in an application described above and which addresses at least one of the disadvantages of the prior art and/or to provide the public with a useful choice.